affectUI vs 21st.dev
21st.dev is a large marketplace of React and Tailwind CSS components, templates, themes, shaders and icons from many authors, with a free account that copies two components a day and monthly or yearly plans that remove the limit. affectUI is one consistent library for AI products – chat, agent trees, fleets, traces, approvals, inboxes – designed together, with a one-time license. Pick 21st.dev for breadth and inspiration, especially heroes and effects; affectUI when the AI product itself should look like one system.
What each one is
- 21st.dev – thousands of React and Tailwind CSS components by many design engineers – heroes, shaders, backgrounds, buttons, AI chats, cards – plus templates, themes, icons and open-source apps. Free accounts browse everything and copy two components a day; Builder, AI and Team plans are billed monthly or yearly. Its CLI and MCP server install components from Cursor, Claude Code and other tools
- affectUI – components, screens and blocks for AI and agent products from one designer, each a single .tsx file with its own CSS and motion, taking plain props
Where they differ
- Breadth: 21st.dev has far more components, in many styles; affectUI has fewer, designed as one system in two matching styles (classic and clean)
- Focus: 21st.dev is strongest on landing pages – heroes, shaders, backgrounds; affectUI on the product – agent trees, fleets, traces, approvals, inboxes, scheduled runs, app screens
- Setup: 21st.dev components build on Tailwind CSS, and what else they need varies by author; affectUI components need only React 19
- Price: 21st.dev is a subscription with a free daily limit; affectUI is paid once, with 40 free MIT items
Where 21st.dev fits better
- You want to browse thousands of ideas and pick single pieces from different authors
- You build a landing page and want animated heroes, shaders or backgrounds
- You prefer a monthly plan and want themes, templates and AI generation in the same subscription
Where affectUI fits better
- Your AI product should look consistent – every component from the same system, with matching spacing, states and motion
- You need agent views – sub-agents, fleets, traces, approvals, background work – designed in depth
- You'd rather pay once than subscribe; Pro stays yours with all future components
- Agent Fleet – Several agents side by side – each card sums up its sub-agents, and a click opens its tree to the right while the last one folds back into its card
- Agent Inbox – All your background agent tasks in one calm list – live clocks and status tags, filter tabs with rolling counts, rows that unfold to the last steps with Approve, Reject, Retry or Open, and glide to their new place
- Trace Waterfall – Where the time and money of an agent run go – every LLM call, tool call and sub-agent as a bar on a live timeline, with tokens and cost per step, the slowest call marked and branches that fold into their parent
Questions
Is affectUI an alternative to 21st.dev?
For the AI product itself, yes – one consistent set of chat and agent views. For browsing thousands of community components and landing effects, 21st.dev has far more, and pieces from both can live in one project.
Is affectUI a subscription?
No. Pro is a one-time license with all future components; 40 items are free under MIT.
Do both work with Cursor and Claude Code?
Yes. Both have a CLI and an MCP server, so coding assistants can find and add components.
Updated 2026-11-03